To accompany the new report Evaluating the Effectiveness of Fish Stock Rebuilding Plans in the United States, the National Research Council has released an interactive chart that lets users see which fish species in the U.S. are being overfished and fished sustainably. http://nas-sites.org/visualization/fisheries/

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Many, But Not All, Depleted Fish Populations Show Signs of Recovery Under Rebuilding Plans That Reduce Fish Harvest

WASHINGTON -- Federal efforts to rebuild depleted fish populations have been successful at reducing fishing pressure on many overfished stocks, and fish stocks have generally increased under reduced harvesting, says a new congressionally requested report from the National Research Council. However, outcomes have been mixed across fisheries; fishing pressure is still too high for some fish stocks, and others have not rebounded as quickly as plans projected.

Much of the variation in performance reflects a mismatch between the current prescriptions for rebuilding within a limited time frame and the uncertainties inherent in assessing and managing fisheries given data limitations and complex ecosystem dynamics where fishing is only one of many influences on fish populations, the report says. Because climate change and other ecological factors can also drive changes in fish stocks, rebuilding fish populations within a certain timeframe cannot be assured.

The report identifies the following strategies for accommodating these uncertainties that, while still promoting rebuilding, could lessen its short-term economic and social impacts for the fishing industry and communities:

§Basing rebuilding plans on monitoring and controlling fishing levels, rather than on requiring that fish populations recover to a pre-specified target size within a certain timeframe. This strategy would be less disruptive to the fisheries and less subject to uncertainty.

§Taking earlier action to avoid overfishing -- imposing gradual limits on fishing when fish populations start to drop rather than waiting until they are overfished. This strategy could help fisheries avoid the stricter limits that come with rebuilding plans.

§Modifying the “mixed-stock exception” to expand the range of situations to which it could be applied. This strategy could also lessen economic impacts relative to current rebuilding plans, which often limit fishing for other healthy species in the same fishery.

About 20 percent of the U.S. fisheries that have been assessed are overfished, according to a 2012 report by the National Oceanic and Atmospheric Administration (NOAA). In most cases, a fish stock is considered overfished when it has been depleted to half the size associated with producing “maximum sustainable yield” – in other words, the maximum, sustainable average amount of fish that can be harvested from a fishery in a year.

When fish stocks drop to an overfished level, the Magnuson-Stevens Fishery Conservation and Management Act (MSFCMA) – the law that regulates U.S. fisheries – requires that fishery managers implement plans that will rebuild the fish stocks, in most cases within 10 years. These rebuilding plans usually require significant restrictions on fishing for the depleted species, limits that may also affect fishing for other species in the same complex. Concerned about the economic and social impacts of these restrictions, members of Congress requested that NOAA fund a National Research Council assessment of the rebuilding plans and their associated ecological and economic effects.

The committee that wrote the report reviewed the current set of federally implemented rebuilding plans and their outcomes. In general, restrictions on fishing included in rebuilding plans have led to growth in fish population size, the report says. Of the subset of 55 fisheries assessed by the committee, 10 are rebuilt and 5 show good progress toward rebuilding. Eleven have not shown strong progress in rebuilding but are expected to rebuild if fishing levels remain reduced, and nine continue to experience overfishing. Recent analyses reveal that 20 of the 55 stocks were not actually overfished despite being classified as such – a finding that reveals the level of uncertainty in assessments of fish stocks and how their perceived status can change as more data become available and assessment methods change over time, the report notes. This uncertainty cuts both ways; though the number cannot be quantified, there is a high probability that some fish stocks that were classified as healthy may actually be overfished.

Much of the variation in performance of rebuilding plans reflects intrinsic limitations in the ability to estimate the size of fish stocks and to set rebuilding targets in the context of complex ecosystems where many factors that affect fish stocks are not predictable or controllable, the report says. This, in part, explains why not all fish stocks rebuild according to the pre-set timeline generally required in rebuilding plans. For example, current plans depend on predicting how much and how fast fish populations will increase if fishing pressure is reduced to various levels. However, there is much uncertainty about how fast fish populations will grow, given the many environmental factors that can affect population size in addition to fishing.

Fishery managers could use additional management strategies to reduce and accommodate environmental variability and uncertainties of rebuilding. Currently, when rebuilding is going slower than expected, fishery managers may impose ever-stricter fishing limits in an effort to meet that deadline. If these managers could instead keep fishing at a reduced but constant level for a longer period of time, they could rebuild fish stocks while allowing higher harvest levels, alleviating some of the socio-economic impacts on the fishing industry and coastal communities.

The requirement to end overfishing for all stocks in mixed-stock fisheries has protected depleted species but has reduced fishing for healthy fish stocks in the same fishery, the report notes. The MSFCMA has a “mixed-stock exception” that offers a way to maintain fishing for healthy stocks, but it has not been invoked, in part due to the narrow range of situations under which it can be applied and also because of the complexity of the issue it is meant to address. The mixed-stock exception could be modified to expand the range of situations to which it could be applied, subject to assurances that the less productive species are not driven to unacceptably low levels, the report says.

Fishery managers can also work to avoid overfishing and rebuilding plans altogether by taking action earlier, the report says. Applying prompt but gradual controls on fish harvesting as the estimated size of fish stocks falls below the Maximum Sustainable Yield level could lower the likelihood that the fish stock will become overfished, and stricter limits may not be needed.

The study was sponsored by the National Oceanic and Atmospheric Administration. The National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council make up the National Academies. They are private, nonprofit institutions that provide science, technology, and health policy advice under a congressional charter. Panel members, who serve pro bono as volunteers, are chosen by the Academies for each study based on their expertise and experience and must satisfy the Academies' conflict-of-interest standards. The resulting consensus reports undergo external peer review before completion. A committee roster follows.

Pre-publication copies of Evaluating the Effectiveness of Fish Stock Rebuilding Plans in the United States are available from the National Academies Press on the Internet at http://www.nap.edu or by calling 202-334-3313 or 1-800-624-6242. Reporters may obtain a copy from the Office of News and Public Information (contacts listed above).

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NATIONAL RESEARCH COUNCIL

Division of Earth and Life Sciences

Ocean Studies Board

Committee on Evaluating the Effectiveness of Stock Rebuilding Plans of the